.. CHIMES Dust Depletion Alexander Richings, 6th March 2020 .. _ChimesDriverDustDepletion_label: Dust Depletion -------------- The ``dust_depletion`` parameter controls how we model the depletion of metals on to dust grains in the chemistry solver. The possible options are described below. +-------------------------------------+------------------------------------------------------------------------------+ | Dust Depletion Model | Description | +=====================================+==============================================================================+ | ``None`` | | The dust-to-gas ratio, is scaled linearly with the metallicity, i.e. we | | | | assume a constant dust-to-metals ratio. However, the abundances of metals | | | | in the gas phase are not reduced to account for the depletion of metals | | | | on to dust grains. | | | | +-------------------------------------+------------------------------------------------------------------------------+ | ``J09`` | | The depletion of individual metals on to dust grains is calculated from | | | | the observationally measured depletion factors (i.e. the fraction of each | | | | element that is in dust) in the Milky Way from Jenkins (2009). These are | | | | expressed as functions of a parameter F_star, which represents the overal | | | | strength of dust depletion and is itself a function of density, | | | | ``n_Htot``. We also impose an upper temperature cut of 1e6 K, above which | | | | all metals are put in the gas phase, to account for the destruction of | | | | dust grains due to sputtering at high gas temperatures. The total dust- | | | | to-gas ratio is then calculated by summing over the depletions of each | | | | individual element. The dust abundances and depletion factors are thus | | | | functions of gas temperature, density and metallicity. See Richings et | | | | al. (in prep) for details of how we implement this model in CHIMES. | | | | +-------------------------------------+------------------------------------------------------------------------------+ | ``DC16`` | | As ``J09``, but using the updated fit parameters from De Cia et al. (2016) | | | | for the individual element depletion factors, where available. For | | | | elements that are not included in De Cia et al. (2016), we use the fits | | | | from Jenkins (2009). See Richings et al. (in prep) for details. | | | | +-------------------------------------+------------------------------------------------------------------------------+ | ``Colibre`` | | The dust-to-gas ratio and depletion factors of individual elements are | | | | calculated as in the COLIBRE model. See Ploeckinger & Schaye (2020) for | | | | details. | | | | +-------------------------------------+------------------------------------------------------------------------------+ References ^^^^^^^^^^ | `De Cia et al. (2016) `_ | `Jenkins (2009) `_ | `Ploeckinger & Schaye (2020) `_